1998 Grand Caravan

So you claim to know most of the engineers in the world, or just most of them in your little world?

I've known 11 personally and 6 of those couldn't pour water out of a boot with directions on the heel.

Reply to
Budd Cochran
Loading thread data ...

Uhh - to you maybe, but everyone else considers it atrocious (oh - sorry

- that's a word that means 'bad'). Or are you just trying to play another shell game with words (morphing the word 'accepted' into 'acceptable')?

Bill Putney (To reply by e-mail, replace the last letter of the alphabet in my address with the letter 'x')

Reply to
Bill Putney

So are you going to apply the same analysis to everyone who works as a mechanic? Hate to tell you, but the ratios of bad mechanics are a lot worse. Let's start with WalMart, Jiffie Lube, independent shops, dealer shops, shops in the back of NAPA stores, etc., etc., etc. - you've gotta throw all those into the mix - i.e., you can't skew the results by eliminating certain categories first before you apply the analysis. :)

Bill Putney (To reply by e-mail, replace the last letter of the alphabet in my address with the letter 'x')

Reply to
Bill Putney

Hi Bill...

Find it terrible terrible hard to believe :)

That's an incredible amount of heat to get rid of; stand well back before the whole thing melts!

Take care.

Ken

Reply to
Ken Weitzel

Hi...

About twenty years ago had 4 dealership mechanics. Defining mechanics all these four were well experienced, all worked together in the same dealership, and at *least* one was fully licensed. (worked on brakes, steering, etc)

They told me, argued with me, that they had found the cure of all energy problems. All they needed to do was attach an electric motor to each wheel, and an alternator to each wheel. Start it going with the gas engine and from then on it would keep going "forever".

They were dead serious. Sent in one of those rip-off applications to one of the USA patent companies, who told them their idea was wonderful, and to send their cheque for further investigation. They sent their cheque. Nothing would convince them not to :)

Ken

Reply to
Ken Weitzel

Your argument isn't very convincing in that, in your lever examples, you appear to be equating force and mechanical advantage with energy loss, and that just isn't inherently the case (the same being true with gear ratios, which I know you correctly related to levers). The energy loss (heat generated) has nothing to do with the mechanical advantage (the distance/force trade-offs) but has everything to do with the friction in the transfer of motion - nothing to do with the lengths of the levers (size of the gears), and everything to do with the reduction of friction at the points of sliding, pivoting, etc.

No offense, but this is exactly the kind of technically incorrect discussion that seems to crop up with those who consider themselves technically savvy in a *hands-on* sense but who put down those with technical (in a *theoretical* sense) expertise. In the same way that you would correctly invoke Archimedes, I would say "Yes, but you also need to consider the law of the conservation of energy which you seem to be ignoring (in your lever examples)". You could move the world with Archimede's lever, but not very rapidly. You could use an opposite lever to move a pea and move it very rapidly. The energy put into the system to accomplish both may be the same - one has a lot of mass moving very slowly, the other has a tiny mass moving very rapidly - the energy calculations are the same - energy applied minus friction losses = energy out.

Now - one implementation of the gears or levers may be more efficient than the other, but it's all in how the friction losses are managed, and not in the mechanical advantage per-se.

There's a place for both "hands on" and "theroetical" - and results are best when they co-exist. Real world follows the laws of physics - what some here disdainfully call "theoretical"; but what many are sarcastically or disdainfully calling the "theoretical" *is/are* the real world laws of physics.

Bill Putney (To reply by e-mail, replace the last letter of the alphabet in my address with the letter 'x')

Reply to
Bill Putney

Yep - just like a week or so ago someone here claiming that an alternator with a working regulator would provide fully regulated voltage no matter what - another perpetual motion machine.

These are the same guys who will out of hand reject engineers for spouting their laws of physics.

Bill Putney (To reply by e-mail, replace the last letter of the alphabet in my address with the letter 'x')

Reply to
Bill Putney

You're right. It has been proposed by some that the "losses" are not real, and are purely a result of the manufacturer's overstated engine output blindly plugged into the efficiency equations with the dynamometer-measured horsepower at the wheels. On the other hand, maybe that's why the ATF properties are so critical.

Bill Putney (To reply by e-mail, replace the last letter of the alphabet in my address with the letter 'x')

Reply to
Bill Putney

Thats another lie. But keep going, I'm beginning to to see a pattern here. The context was "at any RPM", which when speaking of an automobile is anything from idle on up, and nothing below. But of course instead of using facts, you and others stretched things out of context. Nothing new there.

I don't "out of hand reject engineers", I reject those that won't follow good diagnostic method, rely on something other than facts to "prove" themselves correct, and generally lack the basic sense to realize that while they are rejecting proven method, they are describing how they would take six extra steps to find the same info the proven method would reveal.

Reply to
Max Dodge

I wonder where they got the 33% loss figure. Frankly, that sounds like BS to me. If the transmission really is dissipating 1/3 of the engine power input as heat, then you'd need a transmission cooler bigger than the radiator to cool it when running the car hard at all.

Matt

Reply to
Matt Whiting

Methinks you are making the common confusion between power and force (torque). A lever multiplies or divides force (or torque), but it doesn't multiply or divide work or power.

You are the one proposing a violation of the laws of physics. Look up the definition of work and then apply it to both ends of your lever and report back your results.

Matt

Reply to
Matt Whiting

Once again, an engineer talking down to someone, knowing nothing of the other persons credentials... and you wonder why we "common folk" get tired of your crap.

I don't consider it acceptable. In fact, despite my dedicated following of Chrysler, I would never buy something with an A604/41TE etc in it.

Will you next be defining "is"? I ask because you seem to think "accepted" and "acceptable" are terribly different. If you choose to do so, make it succinct (that means 'cut the bullshit out and get to the point')

Reply to
Max Dodge

The gear ratio has virtually nothing to do with it.

Sure, more gears will consume power due to the frictional losses, but this has little to do with the ratios. If you want to change the overall ratio by 6:1, it doesn't matter if you do 3:1 first and then 2:1 or 2:1 followed by 3:1.

Matt

Reply to
Matt Whiting

Nope, never made any such claim nor did Bill. Read again what he wrote, more slowly this time, and see if you can figure out what he said.

You must hang around with a bunch of ignorant people then. I know a couple hundred or more personally (I manager a group with nearly 40) and I don't think 5 of the ones I know could be categorized as you suggest.

Matt

Reply to
Matt Whiting

Mechanic he calls me..LOL...

No....Im just a low life could have been mech e that instead of sticking with MBB.....thats an aircraft firm you now call AirBus BTW, or sticking with the familys business...(thats a Dodge dealership on dads side, and some higher ups with Chrysler over the years on moms) just owns a fairly busy HVAC outfit thats going commercial, and knows what damn idiots most overschooled engineers can be... Of course, you assume as well that I just walked in here..and you cant be farther from the truth...but its ok...its normal for you to assume as thats the way you are taught.

Reply to
CAVHBC

Transmissions 101

Frictional losses are a given in ANY transmission design, as are heat losses and parasitic losses. So, why mention the obvious that, as an engineer, you should know about already?

In an overdrive ratio, do you have more or less usable torque on the output shaft of the gearset? Energy ( torque in), divided ( OD, remember?) by the ratio equals output torque ( minus parasitic losses, of course!!!!) proportionally reduced according to the leverage . . er, ratio of the gearset.

Sorry, it seems I stepped on a toe or two . . .

You assume they are ignored because they are unmetioned. Name a transmission design that generates no friction, heat or parasitic losses????? Now, since there is no such thing, these losses are common and may be set asiode for a discussion of RATIOS AND THEIR EFFICIENCY.

True, I don't deny that and I didn't deny it. It was a metaphor.

Yaes, as in a trebuchet, for example ... nope, I didn't deny this either, bith both of your exaples are fine evdence of the effectiveness of RATIOS dependent, of course, on whether you want to lift a locomotive or throw rocks.

Gear ratios parallel that law.

Agreed, but why are you adding given and common known factors into a discussion on the effectiveness of RATIOS if not to cloud the topic to save your butt?

ROTFLMBO!!!!!!!!!!!

Assume a 20% loss in either transmission to parasitical loss for sake of discussion:

A 1:1 direct drive with a 100 ft.lb. input torque has 80 ft.lb.available from the output shaft out of a theoretical maximum of

100 ft.lb.

A 1:2 overdrive with a 100 ft.lb. input torque has only 40 ft.lb. left out of a theoretical maximum of 50 ft.lb. (This is still theoretical because it doesn't allow for the increased torque loss due to poor mechanical advantage)

Now, tell us again which has the best torque output to run 75 mph with?

Math is "real life", Bill. 1+1=2 And as long as math is a true science it can prove physics.

Budd

Reply to
Budd Cochran

Matt,

I am not confusing the two. I am discussing the EFFICIENCY OF OD RATIOS IN REAL WORLD SCENARIOS in regards to input torque and output torque.

OTOH, I believe you are trying to confuse the discussion.

Budd

Matt Whit>

Reply to
Budd Cochran

Independent shops are often the best source for "outside the box" repairs for items that, according to engineers, can't be repaired. I've done it few times myself.

Now, I can agree readily that I don't consider MOST of the technician staff in Wal-Mart, Jiffy Lube, et al, to be skilled mechanics. Many were hired off the street, I'm sure.

I've never dealt with a NAPA shop except to have brake rotors and drums turned and they older gentleman did an excellent job.

As for dealer shops . . .I've worked in one dealership and only one mechanic in that dealership, the head mechanic, was worth his salt. Btw, no, I was not working there as a mechanic, fyi.

So, yes, certain "categories" can be excluded as they are not trained or experienced mechanics.

Now, should we include medical equipment engineers? Railroad engineers? Ships engineers? Combat Engineers? Hey, all are "engineeers", aren't they?

Budd

Reply to
Budd Cochran

Excuse me, but have the laws of physics been repealed?

(btw, I've only added the parasitic back in because you guys were in tears over their absence.)

If you cut available torque by 2/3+ (frictional losses too) then try to multiply it back by doubling (minus frictional losses) you've got : ((x * .66)*2)- 2FL. OTOH, (x/6)-FL saves a power loss because one less power robbing loss is avoided.

And the other situation is just as bad.

Reply to
Budd Cochran

I'm sorry, didn't mean to speak over your head. It was a reply to the implication of the supposed superiority of the overly educated over that of lowly high school graduates.

Oh, and it was as sarcastic as it reads.

Well, let's see. . . they were the engineers for an automotive muffler factory and one of them came out of his air conditioned office, measured and took notes on a machine built by a member of the millwright crew,, then went in his office, drew up a set of blueprints and took full credit ( and the monetary bonus) for the machine. two weeks later, he ordered extra steel added which took the machine outside design parametres and nearly made it useless.

The rest of what you called "ignorant" were good ol' boys from KY and TN that simply lacked a high school education . . but they weren't stupid.

Send me an email to remind impressed with this later, OK?

Gee whiz, I'll just bet there ain't a single automotive engineering major in the lot of them. And if there is, he's not employed in tha automotive industry. . . .and that makes me wonder "why?"

Reply to
Budd Cochran

MotorsForum website is not affiliated with any of the manufacturers or service providers discussed here. All logos and trade names are the property of their respective owners.